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Abstract

Computing global illumination in complex scenes is even with todays
computational power a demanding task.
In this work we propose a novel irradiance caching scheme that combines the
advantages of two state-of-the-art algorithms for high-quality global
illumination rendering: \emph{lightcuts}, an adaptive and hierarchical
instant-radiosity based algorithm and the widely used (ir)radiance caching
algorithm for sparse sampling and interpolation of (ir)radiance in object
space. Our adaptive radiance caching algorithm is based on anisotropic cache
splatting, which adapts the cache footprints not only to the magnitude of the
illumination gradient computed with lightcuts but also to its orientation
allowing larger interpolation errors along the direction of coherent
illumination while reducing the error along the illumination gradient. Since
lightcuts computes the direct and indirect lighting seamlessly, we use a
two-layer radiance cache, to store and control the interpolation of direct and
indirect lighting individually with different error criteria. In multiple
iterations our method detects cache interpolation errors above the visibility
threshold of a pixel and reduces the anisotropic cache footprints accordingly.
We achieve significantly better image quality while also speeding up the
computation costs by one to two orders of magnitude with respect to the
well-known photon mapping with (ir)radiance caching procedure.